Perhaps one of the most interesting aspects of Lunar photometry is the measurement of Lunar occultations of stars. The darkened limb of the moon provides a knife edge for the star light. Much can be learned from the data obtained. High-speed photometry is used and data points may be logged into a computer at 1 millisecond intervals. The resulting light curve, and resulting diffraction pattern, of the light from the star as it is sliced by the darkened edge of the moon, can reveal multiple stars and information about their configurations. This is a very exciting project because you only get one chance and everything must be just right.

These measurements can be made with either a waxing or waning moon. Measurements can be made from stars disappearing or re-appearing from the darken Lunar limb. Unless you have an exceptionally fine telescope setup and very accurate clock drive, projects involving the disappearance of the stars are the best ones to tackle. At professional observatories where pointing and tracking accuracy of the telescopes is in a few arc seconds, the re-appearance of stars from the darkened Lunar limb can be measure.

For the average amateur, however, being able to point to within a few arc seconds of where the star is to re-appear, and sit waiting many seconds or minutes, is usually beyond the amateur's equipment capability. SKY & TELESCOPE magazine publishes a list of the more popular Lunar occultations occurring during the year, in each January issue. For additional information, refer to LUNAR OCCULTATIONS by Graham L. Blow, section 9 of the SOLAR SYSTEM PHOTOMETRY HANDBOOK.

For additional predictions, contact

Nautical Almanac Office
U.S. Naval Observatory
34th and Massachusetts Ave., N.W.
Washington D.C. 20390 USA

Solar Photometry
Solar photometry offers some unique challenges. Certainly only a small telescope is needed. The problem with solar photometry is just the reverse of other photometry. It's too bright! Because the Sun is a star and we are totally dependent on it, its study is of great importance.

Areas that can be investigated are Sun spots and a quiet (no Sun spot activity) Sun's limb darkening.

For additional information, refer to SOLAR PHOTOMETRY by Gary A. Chapman, section 5 of the SOLAR SYSTEM PHOTOMETRY HANDBOOK.

Planetary Photometry
There has been a growing interest lately in planetary photometry. By observing the light changes as a function of the solar phase angle, information about the objects surface composition can be obtained. There has been recent interest in photometry of the Galilean satellites of Jupiter and work is being done on Saturn's satellites.

For additional information on Planetary Photometry, refer to PHOTOMETRY OF PLANETS AND SATELLITES by G. Wesley Lockwood, section 2 of the SOLAR SYSTEM PHOTOMETRY HANDBOOK.

Planetary Satellite Photometry
Photometry of planetary occultations is another project suitable for the smaller observatory. Doing photometry of Pluto and Charon as the occult each other has been a recent organized project. Recent data published that used UBV photometry were able to show different colors of Pluto and Charon as they occulted each other.

Refer to OCCULTATIONS BY PLANETS AND SATELLITES by Robert L. Millis, section 7 of the SOLAR SYSTEM PHOTOMETRY HANDBOOK.

Asteroid Photometry
Asteroid photometry is a real challenge and requires dark skies and a lot of skill. Asteroids are usually very faint and hard to find. Data obtained on asteroids are of great interest to professional astronomers. Asteroids may someday provide space stations for exploration of the solar system and mining bases for their rich mineral content. By observing asteroid light curves, their rotation rate and surface colors can be investigated.

For additional information, refer to PHOTOMETRY OF ASTEROIDS by Richard P. Binzel, section 1 of the SOLAR SYSTEM PHOTOMETRY HANDBOOK. and ASTEROID OCCULTATIONS by Alan W. Harris, section 8 of the SOLAR SYSTEM PHOTOMETRY HANDBOOK.

Note: The International Occultation Timing Association (I.O.T.A.) is devoted to timing of lunar, asteroid, and planetary occultations. SKY & TELESCOPE magazine usually has details of current projects.

Comet Photometry
This is a very specialized form of photometry and special filters are usually needed. The photometrist with a UBV or VRI photometer can still make valuable observations, however. Before getting too far into comet photometry, it is advisable to contact some of the comet photometry experts. Also, keep an eye out for any new comets. You may be the first to do photometry on them.

For additional information, refer to PHOTOMETRY OF COMETS by Michael F. A'Hearn, section 3 of the SOLAR SYSTEM PHOTOMETRY HANDBOOK.

Nova and Supernova Photometry
While Nova and Supernova photometry are certainly important, it is rare that amateurs have the opportunity for these. They are frequent in other galaxies but are usually beyond the means of most amateur's equipment. Photometry of galaxies is a different story and may well be within the limits of the amateur's equipment.